One way of explaining the Trojan war is to blame it on adultery. There would have been no war if the Trojan prince Paris had kept his hands to himself when he was staying with King Menelaus. Instead he fell for his host's wife, Helen, and carried her off to Troy - so bringing down on his city the wrath of all the Greeks, who came with their 1,000 ships to get the woman back and avenge the honour of the cuckolded king. Centuries before Wolfgang Petersen canonised this version of the story, Greek writers and critics debated the morality of this mythical world war. Surely the punishment, and the terrible loss of life that it brought, was out of all proportion to the crime.

But take a wider focus and the picture looks different. Paris was not purely a bounder who walked off with his friend's wife, but a victim of divine machinations and of the treachery that, in ancient myth, so often marked the dealings of gods with mortals. The story, in this version, goes back to a celebrity wedding between Peleus, a mortal, and his divine bride, Thetis. Uninvited to the festivities, the goddess Strife, true to her name, threw into the party a golden apple inscribed with the words "to the fairest". Three goddesses - Hera, the wife of Zeus, king of the gods, Athena, the goddess of wisdom, and Aphrodite, the goddess of love - instantly started quarrelling about who should have it. Zeus, seeing an awkward decision, set up a mortal to choose the winner. This stooge turned out to be Paris, and his reward for selecting Aphrodite was to be given the most beautiful woman in the world. When he walked off with Helen, in other words, he was in a sense doing what the gods had ordained. The Trojan war was a consequence of divine meddling in human affairs.

The War at Troy, the latest novel from Lindsay Clarke, who won a Whitbread prize for The Chymical Wedding, takes this long view, starting with the marriage of Peleus and Thetis and ending with Menelaus reclaiming Helen at the fall of Troy (his first instinct had been to kill her, but he changed his mind when she innocently - or smartly - dropped the sheet covering her breasts). In many ways it is an engaging retelling of the whole story, neatly blending mythic archaism with modern psychodrama and satire. The judgment of Paris is hilariously recounted, with the poor mortal at first hesitant, but then warming to his task when he realises that an accurate assessment requires that the goddesses take their clothes off. Later, the disintegration of Paris and Helen's relationship as they are cooped up in the besieged Troy proves unexpectedly moving.

Only occasionally does the combination of ancient and modern style jar, in cheesy dialogue or unconvincing character sketches and motivations. Why, for example, does Helen's sister Clytemnestra support the expedition against Troy? Because, Clarke tries to persuade us, she saw the possibility of recouping the money she had squandered on the lavish interior redecoration of her palace in Argos.

But how far are we here from the stories told of the Trojan war by the Greeks themselves? One could say we are very far away indeed. It is not just that Clarke is modernising. He frankly admits that he knows no Greek himself - and when he refers to the "guidance" of Robert Graves's Greek Myths (the 1950s classic which combines a breezy retelling of the stories with mad theories about Mother Goddesses), he means "guidance" in its strongest sense. Most of the episodes in The War at Troy are drawn directly from Graves's book; it is Graves, not Homer, who is Clarke's main "ancient" source.

But another answer is that it is much closer to some versions of ancient storytelling than, I suspect, even Clarke realises. For Graves drew on not just the canonical accounts of the classical Greek myths, but also on slightly later versions, particularly from the Roman period, when writers were often engaged in a strikingly "modern" project: reworking the old stories for a new audience.

Like us, they satirised, up-dated and archaised with considerable verve. More than 700 years after Homer, the Roman poet Ovid wrote a pair of letters, as if between Paris and Helen. Helen's is a variation on the theme that women say "no" when they really mean "yes"; both rewrite the myth in terms of the erotic conventions of Ovid's own day. Another satisfying twist is that the joke about Paris getting the divine trio to undress ("for thorough examination") was already being told almost 2,000 years ago.